1. Field of the Invention
The present invention relates to a power supply shut-off apparatus disposed between a power supply and a load for connecting the power supply and the load through a fuse and for cutting the connection between the power supply and the fuse or the connection between the load and the fuse, and more particularly, to a power supply shut-off apparatus suitable to be mounted on the side of the power supply of an electric car for electrically cutting the connection between the power supply and the load.
2. Description of the Related Art
A knife type power source shut-off apparatus is mounted on a base such that an operation lever of the apparatus can turn around a fulcrum. A receiving terminal connected to the power supply is fixed to one side in the turning direction of the operation lever, and operation terminal is fixed to the operation lever. The operation terminal is connected to a load. The receiving terminal comprises a pair of resilient pieces, and the operation terminal is resiliently sandwiched between the pair of resilient pieces by inserting a plate-like operation terminal between the resilient pieces.
If the operation lever is turned from the right side position into a counterclockwise direction around the fulcrum, the operation terminal is inserted between the resilient pieces of the receiving terminal and resiliently sandwiched therebetween, thereby establishing electrical conduction. If the operation terminal is pulled out between the pair of resilient pieces by turning the operation lever in the clockwise direction from this state so that the operation terminal is separated from the receiving terminal, the electric conduction between the power supply and the load is shut off.
In the case of the knife type power source shut-off apparatus, the electric conduction between the power supply and the load can easily be shut off by turning the operation lever around the fulcrum.
However, if a position between the pair of resilient pieces of the receiving terminal is deviated from orbit of the turning movement of the operation lever, or if positions of the pair of resilient pieces of the receiving terminal are deviated, the operation terminal is deviated toward one of the resilient pieces when the operation terminal is inserted between the resilient pieces, deflection amount of the one resilient piece is increased, the operation terminal receives resilient force more than necessary from the one resilient piece. Therefore, when the operation terminal is inserted between the resilient pieces, excessive force is required.
Also when the operation lever is turned to pull out the operation terminal from between the resilient pieces from the state where the operation terminal is inserted between the resilient pieces, since one of the resilient pieces has greater resistance, excessive force is required.
Therefore, in the case of the knife switch type power supply shut-off apparatus, if the operation lever is deviated from orbit of the turning movement of the operation lever, there is a problem that inserting force and pulling-out force are increase and operability is deteriorated.
Further, if external forces are applied to the operation lever and the latter is turned, there is an adverse possibility that the receiving terminal and the operation terminal are unintentionally connected to each other, and there is a problem that reliably insulation can not be secured.